How to clean up a startup disk on macOS

A full startup disk is something that every Mac user may experience. This problem comes under two different notifications: “Startup disk full” in older macOS versions and “Your disk is almost full” in newer ones. 

Annoying as it may be, it’s an issue that has many solutions, and we’ll cover them in this article. So, let’s find out what exactly “Your disk is almost full” means and how to fix it.

Understanding What “Your Disk is Almost Full” Means

What is a startup disk?

A startup disk, as taken from the Apple Support article, is a volume or partition of a drive that contains a usable operating system. Still confused? Let’s break it down for you.

Your Mac hard drive consists of volumes (or partitions). Each volume (or partition) has your Mac data on it, which consists of your operating system, applications, etc. Most Mac users have just one disk, but power users may have two or more.

Let’s look at an example of a Mac with only one hard disk:

  • Your Mac’s hard drive is 500GB.
  • It has one “disk” on it, so all 500GB of storage is on that disk.
  • The disk has an operating system (macOS Ventura) and user data (apps, etc.). 
  • And since you only have one disk, this is your startup disk — all 500GB.

A Mac with two volumes will have the storage divided between them. The Mac drive with the OS on it is the startup disk, while the other is just used for the storage of files. It’s possible to have multiple startup disks, but most Macs will only have one. And for proper disk cleanup on Mac, all drives are just as important.

Why your disk is almost full?

This is easy. It’s a lot like why is your fridge full? There is no more space! Your disk is almost full, and this is very bad news for any drive. A hard disk should never get beyond 85% capacity (especially a startup disk), as you will experience slowness and errors the further you get above that mark.

If your startup disk is full and you get a message warning from your Mac, this is a serious indication that you need to clear up storage immediately.

How to check your disk space

Now that we’ve identified our startup disk, let’s take a closer look at how to check your disk space:

  1. Click the Apple icon in the menu at the top-left corner of your screen.
  2. Choose About This Mac > More Info.
  3. Click Storage Settings.
System Preferences - Storage

Now that we have the knowledge, it’s time to take action and fix your Mac’s “Startup Disk Full” problem.

How to clear your startup disk

Let’s go over 10 things you can do to help fix “your disk is almost full.” These should also give you other ideas as to how else to fix it — you know your Mac better than we do!

1. Clear system storage on Mac

System storage cleanup sounds like a serious undertaking. But technically, it boils down to just one thing — having the courage to scrap the old files.

  1. Search for large ZIP/RAR archives in Downloads.
  2. Open your Desktop (Command + F3) and delete screenshots.
  3. In Applications, sort your apps by size. Delete the largest ones.
  4. Restart your Mac to free up RAM.
  5. Get rid of system junk files with CleanMyMac X

This app gives you lots of possibilities to free up space, especially when it comes to system junk. CleanMyMac X has been notarized by Apple, which basically means it’s safe to use. And if you got 5 minutes, try this tool as it shows you where exactly your junk hides. Here’s how: 

  1. Download CleanMyMac X for free if you haven’t already. 
  2. Install the app and open it.
  3. Click System Junk from the sidebar. 
  4. Now, click Scan.
  5. Once the scan is complete, you can review details to see what will be removed or click Clean right away and get rid of system junk.
CleanMyMac X - Downloads in System Junk module

That is it! System junk removal has never been easier. The best part about using CleanMyMac is that it removes only those files that can be safely deleted.

2. Clean up cache files on your Mac

Cache files are files that help your Mac run programs a bit more smoothly. Think of them like blueprints for a house: your Mac has the blueprints for how a program is supposed to load/run/look, so it loads it faster; without them, it’d be like building it from scratch. However, over time, these caches can start to take up some serious space. Periodically, removing them can help clear storage. And don’t worry, your Mac will create fresh, new ones after you restart your Mac. To remove caches:

  1. Open a Finder window and select Go in the menu bar.
  2. Click on Go to Folder.
  3. Type in ~/Library/Caches and press Return.
    Delete the files that are taking up the most space keeping the folders.
  4. Now, click on Go > Go to Folder once again.
  5. Type in /Library/Caches (simply lose the ~ symbol)
    And also delete the files that take up the most space.

Deleting cache files is generally safe for your Mac. And once you delete them, the applications and processes you run on your Mac will generate fresh, new ones. But, when deleting, worry more about removing them based on size rather than just removing all of them.

Also, you can check the /System/Library/Caches folder as well, but it might be better not to touch this folder without knowing what the items are. A utility that correctly cleans up these files (and pretty much everything else on this list) is, you guessed it, CleanMyMac X. It cleans up even your system caches with just a few clicks.

And once you’re done with this list, restart your Mac so it can create these new cache files.

Read more: How to Clear Cache on a Mac?

3. Get rid of localization files

Localization files are also known as “language packs.” Lots of apps come with other languages that you probably don’t need. To clear up space on your Mac, delete the ones you don’t need:

  1. Open a Finder window.
  2. Go to Applications.
  3. Ctrl+click on an application.
  4. Select Show Package Contents.

From here, go to Contents > Resources and look for files ending in .lproj. These are the languages your app has, just in case you want to use it in another language, like Spanish (es.lproj). Drag the ones you’ll never use to the Trash.

Again, a safer alternative to this would be to use CleanMyMac X. It gets rid of all of them with a click. No digging through application folders, just a cleaner Mac.

Read more: How to Delete Language Files from macOS?

4. Remove old iOS backups

Backups can tend to take up a lot of space. You can find and remove them by:

  1. Opening a Finder window.
  2. Clicking Go in the menu bar.
  3. Selecting Go to Folder.
  4. Then, typing in ~/Library/Application Support/MobileSync/Backup/ and pressing Return.

Get rid of all the old, outdated backups your Mac has been storing for a bit more extra space.

5. Remove large and old files

Keeping many large files on your Desktop and in Documents slows down the system. And if you delete only a couple of these enormously large files, you can get half of your storage back.

To find large files, you can use the Finder. Here’s how: 

  1. Open the Finder and press Command + F. 
  2. Now, click + top right and choose File Size from the dropdown.
  3. In the next dropdown, choose is greater than and determine the value (for example, 5MB). You can also sort by Date Last Opened or Kind.
  4. Browse the files and send to Trash what you no longer need.

While this instrument is good for finding large files, it misses a lot of things and is too time-consuming. To deepen your search for massive files, use this tool from CleanMyMac X. It’s called Large & Old Files finder.

Archives selected in LAOF module of CleanMyMacX

It’s much more helpful as it shows you lots of other categories of files, like Archives. The app breaks your files by Size and Last Used. 

To see this instrument in action, download CleanMyMac X for free and click the Large & Old files at the bottom of the sidebar. 

6. Optimize your storage 

macOS comes with an easy-to-use tool called Optimized Storage. It is a built-in feature that offers recommendations on how to free up space on Mac. To start using it, repeat the steps you made to the storage (Apple menu > About This Mac > More Info > Storage Settings) or go to System Settings > General > Storage. Under the storage bar, you will see Recommendations, such as Store in iCloud, Optimize Storage, and Empty Trash Automatically. 

Besides, you’ll see the list of categories. By clicking the i next to each of these, you can find out what takes up space and delete unneeded files or apps. 

7. Move your Photos and Docs to the cloud

When your local storage is full to the brim, your Mac will start uploading this data to iCloud. But only if you have this setting enabled. Is your Photos app synced with iCloud already? Let’s check.

  • Open Applications and find the Photos icon.
  • Open Photos and click on Settings in the top menu.

Selecting the box iCloud Photos will connect your Photos library to iCloud. And what’s more important, if you select Optimize Storage from Storage Settings described above, some part of your Photo library will be moved to iCloud. This way, your macOS saves precious space. The free iCloud plan allows you to free up at least 5 GB worth of storage.

A similar logic applies to your Documents and other files. To set up the cloud backup with iCloud drive, go to System Settings > Apple ID > iCloud.

8. Clean up your Downloads, Movies, and Music folders

Have a closer look at these three folders. You’d be surprised at how many downloads can accumulate when you aren’t paying attention. Clean out anything you don’t need (or don’t know) and organize the rest. It’ll take a load off your mind to know that there’s nothing excess there.

The Movies folder can be a pain — not because you’re searching through tons of files, but because it can be difficult to choose what to delete. But alas, sometimes, you need to make sacrifices for the health of your Mac. Though, what you can do with movies you want to keep is to archive them. So, archive what you wish to keep and remove the rest.

How to archive/compress a file

Archiving a file doesn’t mean to store deeper into the abyss of your Mac but to turn the file into something smaller — into a compressed file (like .zip or .tar). By archiving a file, you shave off some memory. Archiving is essential for things you want to keep on your Mac but don’t often use, and it helps you clear up some space. And that’s what this is all about, right? We’re essentially doing the hokey-pokey on your Mac. To archive a file, just:

  1. Control-click the file you want to compress (recommended for movie files).
  2. Select Compress.

The last place to sweep through is the Music folder. Find and remove duplicate music files first and then clean up all the songs you downloaded on a weird Sunday afternoon cleaning the house.

9. Clean your Desktop

“Clean my desktop… but why?” Because some people’s desktops are hard to look at, that’s why. Organize your desktop and get rid of the stuff you just don’t need on there. It looks better and helps your Mac act a bit faster (we don’t know the rocket science behind this one, but it feels too good to be false). Your Mac doesn’t waste time loading all those icons and junk, but just clean it, please.

10. Empty out the Trash (No, we’re not joking…)

It may sound incredibly basic, but it could clear a surprising amount of storage. We forget to do it all the time. The thing is that when you delete something, your Mac doesn’t remove it — it just moves it to the Trash. Plus, you’ve probably deleted way more than you realize, and all that could be sitting in the Trash, wasting space. So get rid of all that junk by emptying the Trash:

  1. Control-click your Trash in the Dock.
  2. Select Empty Trash.
  3. And click Empty Trash.

And the easiest step is done.

We’ve told you how to delete storage on Mac in multiple ways. Hopefully, this has helped you fix that full startup disk problem. Your startup disk should now be quite a bit lighter. If you liked this article, get social with it to help others in need. And if you really liked this article, subscribe to our email list — we’ve got more guides on the way.  

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